Suppression of luteal phase, but not midcycle, prolactin levels by chronic follicular phase opiate antagonism

Robert G. Brzyski, Amabel Viniegra, David F. Archer

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Objective: To investigate whether establishment and maintenance of chronic opioid blockade throughout the follicular phase of the menstrual cycle influences midcycle and luteal phase prolactin levels. Design: Randomized, double-blind, crossover study. Setting: Academic research environment. Patient(s): Volunteers, aged 21-35 years, with regular menstrual cycles. Intervention(s): Naltrexone (50 mg) or placebo were administered on cycle days 2-14. Blood samples were obtained in the early follicular phase and in the periovulatory and midluteal phases of the menstrual cycle. Main Outcome Measure(s): Serum prolactin levels. Result(s): In the early follicular phase, serum prolactin levels were equivalent in naltrexone (12.0 ± 2.7 μg/L; mean ± SE) and placebo (12.1 ± 2.9 μg/L) cycles. A statistically significant increase in serum prolactin was observed on the day of the LH surge (naltrexone: 22.6 ± 3.7 μg/L placebo: 21.7 ± 2.7 μg/L; P < 0.05 versus early follicular phase), but no difference between treatments was observed. However, midluteal prolactin levels were statistically significantly lower in naltrexone cycles compared with placebo cycles (12.6 ± 3.3 versus 15.4 ± 3.0 μg/L; P < 0.05). Conclusion(s): Chronic blockade of opioid activities during the follicular phase does not affect midcycle prolactin increments, but withdrawal of opioid blockade may enhance opioid effects on prolactin levels in the luteal phase.

Original languageEnglish (US)
Pages (from-to)855-859
Number of pages5
JournalFertility and sterility
Issue number5
StatePublished - Nov 1997
Externally publishedYes


  • Menstrual cycle
  • Naltrexone
  • Opioid peptides
  • Prolactin

ASJC Scopus subject areas

  • Reproductive Medicine
  • Obstetrics and Gynecology


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